Thomas Weinhart


MercuryCG – From Discrete Particles to Continuum Fields

Thomas Weinhart
Micro–macro transition methods are used to both calibrate and validate continuum models from discrete data, obtained from either experiments or simulations. Such methods generate continuum fields such as density, momentum, stress, etc, from discrete data, i.e. positions, velocity, orientations and forces of individual elements. Performing this micro–macro transition step is especially challenging for heterogeneous and dynamic situations. Here, we present a mapping technique, called coarse-graining, to perform this transition. This novel method has several advantages: by construction the obtained macroscopic fields are consistent with the continuum equations of mass, momentum and energy balance. Additionally, boundary interaction forces can be taken into account in a self-consistent way and thus allow for the construction of locally accurate stress fields even within one element radius of the boundaries. Similarly, stress and drag forces can be determined for individual constituents, which is critical for e.g. mixture and segregation models. Moreover, the method does not require ensemble-averaging and thus can be efficiently exploited to investigate static, steady and dynamic flows. The resulting fields may serve various purposes: an in-depth analysis of the material behaviour; extracting a problem-specific continuum model; or even coupling of particle simulations with fluid solvers or other continuum models.
We show how to practically use coarse-graining for both steady and dynamic flows and mixtures, using our open-source coarse-graining tool MercuryCG. The tool is available as part of an efficient discrete particle solver MercuryDPM

Bio Sketch:

Thomas Weinhart
• Assistant Professor in Multiscale Mechanics, Dept. of Thermal and Fluid Engineering, University of Twente
• Developing simulation methods to understand, predict and optimize complex multi-physics, multi-scale processes
• Focus on granular systems, using the Discrete Particle Method, CFD, and coupled simulation techniques
• Cofounder of simulation software MercuryDPM, spin-off company MercuryLab
• Developed MercuryCG, an accurate and efficient technique to analyse discrete simulations, and couple them with continuum models
• Developed microscopic contact models for frictional, wetted and sintered particles, as well as rheological laws for granular and atomistic flows and mixtures
• Applications: segregation and mixing, avalanche flows, additive manufacturing, wet agglomeration, tableting, etc.